How to move a mesh without disturbing origin point
Simplest way is switching to Edit Mode and moving the mesh instead of moving the object in Object Mode, thus the origin stays in place: 




Select the object
Toggle to Edit Mode Tab
Hit A to make sure all vertices/edges/faces are selected
Move the mesh via Grab/Move G or simply use the 3d Manipulators


In order to get precise control about moving the mesh, also see:


Is there a shortcut or hotkey that I could use to access the Transform panel of the properties shelf in the 3D viewport?
How do I rotate and scale edges in Edit Mode?
Constrain to any 2 axes during transform?